Does Leading Modality Influence Multisensory Integration in Children with Autism?
Objectives: Assess the contribution of leading modality on tolerance of asynchrony in children with ASD vs typical children at different periods of development.
Methods: Eighty-six participants were separated into ASD child (n=17; age <12), ASD adolescent (n=13; age > 12), TD child (n=30; age <12) and TD adolescent (n=26; age > 12) groups. Participants evaluated the simultaneity of audiovisual stimulus pairs at seven varying stimulus onset asynchronies (SOAs: 50ms, 100ms, 150ms, 200ms, 250ms, 500ms, 750ms) with 7 SOAs presented audio-leading (A-L), 7 SOAs visual-leading (V-L), and one synced (Powers et al., 2009). Participants were asked to respond whether the auditory stimuli (10ms, 1800 Hz pure tone) and visual stimuli (white annulus subtending 9 visual degrees) were presented at the ‘same’ or ‘different’ time.
Results: Proportion of ‘same’ responses were calculated for each participant. A 3-way mixed ANOVA (4 groups x 2 leading modalities x 7 SOAs) revealed an overall significant effect of leading modality (p <0.001), with V-L trials being indicated as synchronous more often than A-L trials, suggesting a greater tolerance for asynchrony for visual-leading stimulus pairs. No significant overall effect of group was found. However, a significant modality by group interaction was found (p <0.001). This effect is explained by a shift in modality sensitivity across age, mediated by group. Whereas only small changes in proportion of ‘same’ responses occurred across age for the ASD group (children; MA-L =62.43 vs MV-L =68.25 | adolescents; MA-L =51.65 vs MV-L =60.71). Meanwhile, a larger difference in audio- vs visual-leading trial performance was found for the TD group (adolescents; MA-L =53.00 vs MV-L =67.45 | children; MA-L =54.68; MV-L =61.23).
Conclusions: Asynchrony was tolerated to a greater extent in V-L stimuli for all groups. However, performance was mediated by age group, with a larger developmental jump in visual- vs auditory-leading performance in TD groups compared to ASD groups. Our results provide evidence for atypical development of MSI in individuals with ASD, as defined by tolerance to asynchrony, and provide a platform for further investigation of the developmental trajectory of MSI in this population.
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